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P 14-42 kitzoom softness.

Discussion in 'Native Lenses' started by Rachotilko, Jan 1, 2013.

  1. Rachotilko

    Rachotilko New to Mu-43

    3
    Dec 18, 2012
    Hi, I am new here - a new M43 owner.

    I have bought the G3+14-42 kit. As a part of my testing process I shot some wideangle shots. I was prepared to see some corner softness, but this surprised me:
    [​IMG]
    The image is composed of three shots and shows the same tree.
    1. First time, the tree was located in the image's corner, the shot was taken @f/3.5
    2. The middle part shows the corner shot @ f/8
    3. The last third is when the tree was in the center of the image, f/3.5

    My question is: is this softness normal ? If I apply for warranty repair/replacement, is there a chance of receiving a better unit ? I know there are better lenses out there, but I right now have to live with this model. So: should I just live with it or should I bother applying for the warranty repair ?
     
  2. coffeecat

    coffeecat Mu-43 Top Veteran

    709
    Aug 4, 2012
    SW England
    Rob
    Just to clarify, what focal length was this shot at?
     
  3. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    Also, was this all shot at the same focal point, or could it be that the AF was picking something else to focus on, causing it to be slightly out of focus (but by f8, had enough DoF to help)?
     
  4. Rachotilko

    Rachotilko New to Mu-43

    3
    Dec 18, 2012
    Focal length was 14 mm.

    I set the focus mode to "single area", made that area small enough and pointed it to the tree: when the tree was in the corner, I pointed the focus to the corner, when I turned and the tree was in the center, I pointed the focus to the center.

    It was 100% focused correctly on the tree.

    BTW, sorry for my English
     
  5. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    Thanks for the clarification, was just trying to think of other possibly simple "user error" kind of things.
     
  6. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    Would a 'perfect' copy of this lens do any better than your copy?
    Personally I'm not sure, it doesn't have a great reputation so far.

    Buy hey! It fits in a pocket right?
     
  7. coffeecat

    coffeecat Mu-43 Top Veteran

    709
    Aug 4, 2012
    SW England
    Rob
    Hi,

    I can't really say whether your copy is good or bad, but the lens certainly has much better sharpness at centre than at corners at 14mm.

    There are reviews here

    Review Panasonic 14-42 mm f/3.5-5.6 ASPH MEGA OIS LUMIX G VARIO (m43)

    Panasonic Lens: Zooms - Panasonic 14-42mm f/3.5-5.6 ASPH MEGA OIS LUMIX G VARIO (Tested) - SLRgear.com!

    Panasonic 14-42mm f/3.5-5.6 Micro Four Thirds Zoom Lens Review

    They all tell much the same story.

    There are lab photos in the slrgear review, eg. here


    http://www.slrgear.com/reviews/zsamples/Panasonic14-42f35-56g/zpanasonic14-42f35-56vfa014f35_g3.jpg

    I did a quick non-scientific test of my own (no tripod, but manual focus and exposure) at 14mm, f3.5, ISO 400, LR4 jpeg exports from RAW, no PP, results here:

    Centre:
    P10300881.
    Corner:
    P1030089.

    To my eyes, my lens is clearly softer corner vs centre, as you'd expect, although the most noticeable difference seems to be vignetting! I'm not totally convinced I nailed the focus, unfortunately...

    Sorry though, to end as I started off with, I don't think I can really say whether yours is a good or bad one... But I've had a lot of fun using this lens as my main lens for the first 6 months of m43 ownership.

    Rob
     
  8. Rachotilko

    Rachotilko New to Mu-43

    3
    Dec 18, 2012
    Conclusion

    First, thanks you guys for your replies. All of them were helpful !

    Coffeecat, the most helpful resource you posted was the "lab" shot from slrgear. I created some black squares on white paper to create my homebrew "target" and compared it with reference one from slrgear. I measured the number of blured pixels at the "black-white" or "white-black" transitions.

    At first my lense's results were even worse that reference. I did not give up and tried to focus completely manualy (in the corner of course). And alas ! I achieved the same results - which are very far from perfect in absolute terms, but I am happy now that my lense is not a faulty copy.

    But question remains as to why did the CDAF fail to find the sharpest focusing ? My conclusion is that AF can be mislead if the selected area happens to exhibit a strong chromatic aberration (CA). It would take some analysis of transfer functions but my guess is that in the presence of CA, the most contrasty focusing position does not corespond exactly to with the most sharp one.

    I am happy with this hypothesis for the moment.
     
  9. coffeecat

    coffeecat Mu-43 Top Veteran

    709
    Aug 4, 2012
    SW England
    Rob
    Hi Rachotilko,

    glad to be of some help!

    I've got a huge amount of help/inspiration/knowledge from the members of this website (partly from directly answered questions, but mainly from just reading people's posts). It's nice to be in a position to give something back now and then, however small.

    Your CDAF theory is interesting. Transfer functions - reminds me why I dropped electronics as soon as I could in my engineering degree!

    Rob